Purpose: Aromatase inhibitors have improved breast cancer outcomes for early stage, postmenopausal women who have hormone receptor positive disease. Aromatase inhibitors have replaced the prior gold standard treatment, tamoxifen, a selective estrogen receptor modulator However, aromatase inhibitors markedly reduce estradiol and have the potential to increase the risk for osteoporosis and associated bone fractures. Guidelines for monitoring bone health in women with breast cancer exist but it is unclear whether these recommendations are the standard of care in Hawai'i. This study addresses adjuvant chemotherapy among women with early stage breast cancer and related issues of bone health in Hawai'i.
Methods: The patients were women age 50 and older with early stage breast cancer who were taking an aromatase inhibitor or tamoxifen and enrolled with the largest insurer in Hawai'i from 1999 to 2006. Their clinical histories were obtained from administrative data including their prior use of hormone replacement therapy and whether they had received radiation or adjuvant chemotherapy. Spine, hip, and wrist fractures, bisphosphonate therapy, and dual energy X-ray absorptiometry scans were the measured outcomes.
Results: In 2006, the percentage of women on tamoxifen was 29% compared to 71% for aromatase inhibitors. Women taking aromatase inhibitors were significantly more likely to have bone fractures than those on tamoxifen (rate ratio = 2.42). More patients on aromatase inhibitors received bone density scans as well as medications to prevent bone loss (odds ratio = 1.86).
Conclusions: In this Hawai'i population, the use of aromatase inhibitors has increased steadily since 2002 when the initial adjuvant trial for postmenopausal women with early breast cancer was reported. However, tamoxifen remained a commonly prescribed agent. Women taking aromatase inhibitors were at increased risk of developing fractures. In addition, preventative strategies, such as dual energy absorptiometry scans and bone health agents, were underutilized.